The invention relates to a device for negative pressure wound therapy comprising (a) a cover material for air-tight sealing of the wound space; (b) as applicable a means for the connection of a negative pressure source and (c) a wound dressing comprising an open-cell polyurethane foam, whereby the open-cell polyurethane foam has special characteristics, in particular a tensile strength after three days of storage in bovine serum, measured in accordance with DIN 53571, between 80 kPa and 300 kPa. The invention further relates to the use of said an open-cell polyurethane foam as a wound dressing in negative pressure wound therapy.
A wound is defined as the separation of the coherence of tissues of the outer body of humans or animals. It can result in a loss of substance.
Devices for the negative pressure wound therapy are known in the prior art. For example WO 1993/009727 A1 describes a device to promote healing of the wound by the application of a negative pressure on the skin area which is wounded and the area surrounding the wound. The device according to WO 1993/009727 A1 comprises a negative pressure device to generate the negative pressure, an air-tight cover of the wound which has a functional connection with the negative pressure device, as well as a wound dressing for positioning on the wound inside the air-tight cover.
Devices for the negative pressure wound therapy are commercially available, for example the V.A.C.® device from the company KCI. Commercially available devices often use a wound dressing which contains an open-cell polymer foam such as polyvinyl alcohol (PVA) or polyurethane (PU).
The commercially available foam dressings are compressed to a different degree, depending on the negative pressure applied. This can cause a constriction of the passages necessary for the removal of the wound exudate. Adhesion of the foam with the wound can also occur. Newly formed tissue can grow into the wound. This problem is a familiar complication in the negative pressure therapy of wounds (FDA complaint data base). In order to solve this problem, additional wound contact layers are often introduced between the foam and the wound, for example a film (see, for example, WO2001/85248). However, these additional wound contact layers can reduce the passage of wound exudate.
When the wound dressing is to be changed, elaborate measures have to be taken to remove adhered foam, for example by rinsing with Ringer's solution. Tissue which has grown into the foam can lead to a tissue traumatization when the wound dressing is removed and thus delay the healing process.
When conventional wound dressings are used, particles of foam can also enter the wound. These can irritate the wound and delay the healing process. This problem is aggravated if the wound dressing is cut to the size of the wound before being applied, as this results, in particular, in loose foam particles at the cut edges.